Biostatistics Seminar: Daniel Tancredi, Pediatrics, UC Davis

TITLE:Practical considerations for sample size calculations in clinical research

ABSTRACT: “How many subjects do I need?” is a common question asked of medical statisticians. Appropriate power and sample size calculations may promote the scientific, ethical and economic soundness of clinical research studies. However, many clinical research studies are undertaken with seriously defective or even no power calculations. In this seminar, we will identify key design and analysis features that affect the statistical power of a study to detect clinically meaningful effects but that are often neglected. We will also illustrate some practical methods for accounting for such features, including longitudinal measurement, cluster randomization, unknown values for nuisance parameters, and the use of generalized linear models.(1-2) We will also discuss the “sample size samba” and some of the other flaws and potential harms that arise from contemporary sample size conventions.(3)